1. Field of the Invention
The present invention generally relates to an image magnifying/reducing optical device used in an apparatus for displaying an image or taking an image, and a manufacturing method thereof, and, in particular, a two-dimensional magnifying/reducing optical device having advantages in that a light quantity is uniform throughout the device, and the device can be rendered thinner and light-weighted, and, other extremely remarkable advantages, and a manufacturing method thereof.
2. Description of the Related Art
Display apparatuses for displaying information include two types of ones, i.e., equal-size display apparatuses such as liquid-crystal monitors for personal computers called flat-panel display devices and magnifying projection display apparatuses such as rear-surface projection liquid-crystal televisions and so forth. In the equal-size display apparatus, it is possible to reduce the thickness of a display device, and, thereby, this requires a reduced space for setting it. However, when a large-sized screen is required, such as 30 inches or more, for example, a considerably high cost is needed due to complicateness of manufacturing process, a low production yield, and so forth. On the other hand, with regard to the magnifying projection display apparatus, it is possible to provide a large-sized display screen such as 50 inches or more while requiring a cost lower than that for the equal-size display apparatus. However, it is difficult to reduce the thickness of the display device in the magnifying projection display apparatus to that of the equal-size display apparatus, due to a reason for the principle thereof. Accordingly, a larger space is needed for setting the magnifying projection display apparatus.
In a conventional magnifying projection display apparatus such as a liquid-crystal television, a method of magnification by using a lens or a mirror is employed. Other than this, as shown in FIG. 1, optical fibers 11 are arranged for a small image, and, as a result of the optical fibers 11 being disposed discretely, the image is magnified (see Japanese Laid-Open Patent Application No. 05-88617, referred to as a method A). Further, as shown in FIG. 2, an image is magnified by using a plurality of blocks 1a, 1b each being obtained from cutting a set of optical fibers, obliquely (see Japanese Laid-Open Patent Application No. 06-51142, referred to as a method B). Furthermore, as shown in FIG. 3, in order to magnify displayed images of a plurality of liquid-crystal display panels 2a, 2b, . . . , 2n, these displayed images are transmitted to a display panel 4 by using optical fibers 3 (see Japanese Laid-Open Patent Application No. 09-252444, referred to as a method C). As shown in FIG. 4, a displayed size of each pixel is magnified by using tapered optical waveguides 3 (see Japanese Laid-Open Patent Application No. 07-43702, referred to as a method D).
In the above-mentioned method A shown in FIG. 1, although the area of the displayed image is magnified, the pixels are disposed discretely, while each pixel itself is not magnified.
In the above-mentioned method B shown in FIG. 2, it is difficult that light is coupled from the block 1a to the block 1b at high efficiency. Furthermore, it is very difficult to align the block 1a with the block 1b at high accuracy when the blocks 1a and 1b are bonded together in a manufacturing process, in a case where the diameter of each optical fiber is very small.
In the above-mentioned method C shown in FIG. 3, it is possible to render a thin, seamless wide screen display apparatus by combining display apparatuses 2a through 2n having small screens. However, same as in the above-mentioned method A, each pixel itself is not magnified.
In the above-mentioned method D shown in FIG. 4, although each pixel itself is magnified, the pitch between the pixels is not magnified. Accordingly, the entire image is not magnified.
Other than them, in one method, an image is magnified by using a through hole of a metal (see Japanese Laid-Open Patent Application No. 5-80319). In another method, an image is magnified by using a reflection metal plate (see Japanese Laid-Open Patent Application No. 7-294757). However, when optical transmission by using a metal reflection plate is employed, differently from optical transmission methods employing optical fibers or optical waveguides, loss of light through reflection is large, and, as a result, it is not suitable for a practical use.
Further, as a demand for apparatuses for reading images such as a facsimile machine, an image scanner, a digital copier, and so forth, it is desired to miniaturize an image sensor which converts image information into an electric signal, and development of a miniaturized image reducing device is desired. For example, as a method of transmitting a one-dimensional image read from a wide original into a small one dimensional CCD, a method has been proposed in that tapered optical waveguides are arranged on the original surface, and reduced areas of the optical waveguides are used for coupling to the CCD (see Japanese Laid-Open Patent Application No. 09-37038). This method is advantageous when it is used for magnifying/reducing one-dimensional image. However, this method is not used for magnifying/reducing a two-dimensional image.
Further, a product for magnifying/reducing an image by not using a lens has been on sale as a name of xe2x80x9cTaperMagxe2x80x9d from Taper Vision Co. Ltd. of United States. In this device, many optical fibers are bundled up at high density, and are molten so as to be tapered. However, in this configuration, as glass fibers are bundled and worked, it is difficult to provide a large-scaled display area more than 100 mm square. Further, it is difficult to increase the tapering angle by the reason for a working process. In fact, when a display screen on the order of 30 inches is to be provided, it is not possible to reduce the thickens of the device less than 30 cm.
Further, although various manufacturing methods have been proposed for optical waveguides, they include methods for manufacturing a single fiber or a one-dimensional fiber array, but do not include a method for manufacturing a two-dimensional array which has a three-dimensional complicated shape- For example, Japanese Laid-Open Patent Application No. 11-326660 discloses a method of forming an opitcal waveguide along an optical axis by causing a specific light to be incident on photo-curing resin. However, this method merely produces a single optical waveguide, but does not produce a two-dimensional optical device made of a plurality of fiber arrays. Further, according to Japanese Laid-Open Patent Application No. 5-157923, ions are provided into glass by electric field, and thereby, three-dimensional optical waveguide is produced. However, this method is not practical for producing a complicated structure which is desired for the present invention.
Further, Japanese Laid-Open Patent Application No. 07-230018 discloses a method of producing a tapered optical waveguide at an extending end of an optical fiber. In this method, an optical fiber is immersed into photo-reacting substance, and ultraviolet light is applied into the optical fiber. However, in this method, the fiber used is a quartz single-mode optical fiber. Also, this publication discloses neither specific ultraviolet light source nor specific ultraviolet-curing material.
An object of the present invention is to solve the above-mentioned problems, and thus, to provide a thin two-dimensional image magnifying/reducing optical device by which the entire image and also each pixel size can be magnified/reduced without employing a conventional projection system, and a manufacturing method therefor.
An image magnifying/reducing optical device according to the present invention comprises:
a base member having first and second surface which are approximately parallel to one another; and
a plurality of high-refractive-index regions formed in said base member,
the plurality of high-refractive-index regions continuously extending from the first surface to the second surface of the base member; and
a sectional area of each of the plurality of high-refractive-index regions around the second surface being larger than that around the first surface.
In this configuration, light incident on the high-refractive-index region and reflected by the interface with a low-refractive-index region is transmitted by the high-refractive-index region, from the first surface to the second surface. As the cross-sectional area of the high-refractive-index region is different between the first and second surfaces of the device, an image input to one surface is magnified/reduced through the device, and is output from the other surface. Thus, magnifying display of an image/reduction reading of an image can be rendered by the device.
Further, in this configuration, it is possible to yield a light-weighted device in comparison to an inorganic glass.
Further, when light is transmitted through each high-refractive-index region, the light is not mixed with light transmitted through another high-refractive-index region. Thereby each pixel can be positively enlarged.
Each of the plurality of high-refractive-index regions may extend approximately perpendicular to at least one of the first surface in the vicinity thereof and the second surface in the vicinity thereof.
Thereby, it is possible to achieve uniform light quantity throughout the device with a thin configuration of the device, and to easily produce the device.
A diameter of each of the plurality of high-refractive-index regions may be approximately fixed in a position in which a center-axis line thereof is inclined from a normal of the second surface by not less than 45xc2x0.
Thereby, it is possible to yield a thin device and to produce the device easily.
A cross-sectional area of each high-refractive-index region may be increased gradually in the vicinity of the second surface, and has a tapered shape.
Thereby, the shape of each fiber (high-refractive-index region) can be simplified, and a thin device can be yielded.
A cross-sectional area of each high-refractive-index region may be increased after being decreased from that on the first surface.
Thereby, it is possible to yield a further thinner device.
A micro lens may be disposed for one of the first and second surfaces, the one of the first and second surfaces being a surface on which light is incident for changing a size of an image.
Thereby, it is possible to reduce loss of light input to each fiber (high-refractive-index region).
One of a light absorbing layer and a metal film may be provided on a side surface of each high-refractive-index region.
Thereby, it is possible to avoid stray light between adjacent fibers (high-refractive-index regions).
Each high-refractive-index region may have one of a convex surface and a concave surface on at least one end surface thereof.
Thereby, it is possible to improve efficiency of taking light into each high-refractive-index region, and, also, to enlarge the angle of visibility of an image output from the device.
At least a part of each high-refractive-index region may be joined by a mesh-like high-polymer member having a shrinkable property in at least a part thereof.
Thereby, it is possible to automatically bundle the fibers (high-refractive-index regions) without disarrangement of the fibers.
At least a part of each high-refractive-index region may be joined by a member which can enter a gel-like state in at least at a part thereof.
Thereby, it is possible to automatically bundle the fibers (high-refractive-index regions) without disarrangement of the fibers. Also, it is not necessary to apply a force for expanding the member.
A relative relationship between the plurality of high-refractive-index regions on the first surface may be also maintained on the second surface.
Thereby, an image input to the device is maintained through the device without distortion.
A ratio of a cross-sectional area of each high-refractive-index region on the first surface to a cross-sectional area thereof on the second surface may be approximately uniform throughout the plurality of high-refractive-index region.
Thereby, an input image can be magnified without distortion.
The plurality of high-refractive-index regions may comprise at least a part at which a center-axis direction of the high-refractive-index region is inclined from a normal of the base member by not less than 45xc2x0.
Thereby, it is possible to effectively reduce the thickness of the device.
An angle between light transmitted by the high-refractive-index region when it is incident on the first surface and a normal of the base member is not more than 30xc2x0 in the vicinity of the first surface.
Thereby, it is possible to improve the coupling effect of the incident light, and, as a result, to render the transmission efficiency of an image uniform throughout the device.
An angle between light transmitted by the high-refractive-index region when it exists from the second surface and a normal of the base member may be not more than 30xc2x0 in the vicinity of the second surface.
Thereby, it is possible to reduce the view angle dependency for each pixel.
A cross-sectional shape of each high-refractive-index region may be approximately squire on the second surface.
Thereby, in comparison to circular cross section, it is possible to increase an area through which an image is transmitted in the device.
A cross-sectional shape of each high-refractive-index region may be approximately hexagon on the second surface.
Thereby, in comparison to circular cross section, it is possible to increase an area through which an image is transmitted in the device. Also, in comparison to a square cross section, a curved shape can be smoothly displayed.
The plurality of high-refractive-index regions may comprise high-polymer fibers.
Thereby, it is possible to yield a thin, inexpensive, light-weighted image magnifying/reducing optical device.
The high-polymer fiber at any position has a length lx satisfying the following formula (1):                                                         t              ⁡                              (                                  n                  +                  1                                )                                      ⁢                          (                                                                                                                  ∑                                                  a                          =                          1                                                N                                            ⁢                      Sa                                                                                      ∑                                                  a                          =                          1                                                N                                            ⁢                      sa                                                                      -                1                            )                                +                      l            min                          ≥        lx        ≥                              l            min                                sin            ⁢                          xe2x80x83                        ⁢            θ                                              (        1        )            
where:
N denotes the total number of the fibers;
a denotes the number of each fiber;
Sa denotes the area of the end surface of the fiber a on the second surface;
sa denotes the area of the end surface of the fiber a on the first surface;
lmin denotes the length of the shortest fiber;
t denotes the averaged fiber interval on the first surface;
n denotes the number of fibers present between the relevant fiber and the shortest fiber; and
xcex8 denotes an angle of the straight line passing through the position of the relevant fiber on the first surface and the position of the same fiber on the second surface with respect to the first surface.
Thereby, the surface of the device can be rendered smooth, and the thickness of the device can be effectively reduced. Also, brightness uniformity throughout the device can be achieved.
The refractive index n1 of the plurality of high-refractive-index regions and the refractive index n2 of a low-refractive-index region surrounding the high-refractive-index regions may satisfy the following formula:
n12xe2x88x92n22xe2x89xa70.07
Thereby, it is possible to improve the efficiency in taking light into and transmission thereof through the high-refractive-index regions, and thus, to increase brightness in the transmitted image
The refractive indexes n1 and n2 may satisfy the following formula:
n12xe2x88x92n22xe2x89xa70.25
Thereby, the performance can be further improved.
A cross-sectional area of the high-refractive-index region may be smaller than those on the first and second surfaces at least a part thereof.
Thereby, it is possible to effectively reduce the thickness of the device. Further, even if a member for bundling the fibers remains between the fibers, the fibers can be arraigned closely at both ends thereof.
Each high-refractive-index region may have an extending-end expanding-tapered shape such as to increasing a cross-sectional area gradually in at least one of the proximity of the first surface and the proximity of the second surface.
Thereby, it is possible to effectively reduce the thickness of the device.
The following formula (4) may be satisfied:
b less than 252/(1xe2x88x92X)xe2x80x83xe2x80x83(4)
where:
b (xcexcm2) denotes a cross-sectional area of at least a part of the high-refractive-index region other than both end parts thereof; and
X denotes a value obtained from dividing a cross-sectional area of the high-refractive-index region on the first surface by that on the second surface, where X less than 1.
Thereby, in a case where an image having more than ten million pixels is taken in or output with 200 dpi, for example, it is possible to provide the device having the thickness of not more than 4 cm.
An image magnifying display device according to the present invention comprises:
the above-mentioned image magnifying/reducing optical device according to the present invention; and
a display unit disposed so as to face the first surface of the image magnifying/reducing optical device.
Thereby, without using a conventional projection-type device, it is possible to render magnification of image itself and pixel size through a thin configuration.
An image reducing reading device according to the present invention comprises:
the image magnifying/reducing optical device according to the present invention; and
a two-dimensional solid image pickup device disposed so as to face the first surface of the image magnifying/reducing optical device.
Thereby, it is possible to render reduction of image itself and pixel size through a thin configuration.
A method of manufacturing the above-mentioned optical device, comprises the step of a) making the high-polymer fibers from photo-curing resin.
The method may further comprise the steps of:
b) forming the high-polymer fibers by applying high-directivity light to the photo-curing resin; and
c) bundling the thus-formed fibers so as to yield the plurality of high-refractive-index regions.
Thereby, it is easy to produce the optical device.
The method may further comprise the steps of:
d) disposing one end of a bundle of the fibers in a close collected state;
e) disposing the other end of the bundle of the fibers in a spaced state;
f) immersing the other end of the bundle fibers into photo-curing resin mixed solution; and
g) applying light into the one end of the bundle of fibers so as to form tapered parts extending from the other end of bundle of fibers.
Thereby, the tapered parts can be produced automatically.
The method may further comprise the steps of:
d) disposing a substrate having one of a convex shape and a concave shape for each fiber of the bundle of fibers; and
e) applying light toward the substrate in the photo-curing resin so as to form one of a concave shape and a convex shape on an end surface of each fiber of the bundle of fibers.
Thereby, the concave/convex end surface of each fiber can be automatically formed.
The method may further comprise the steps of:
b) providing one of a light absorbing layer and metal film on a side surface of each high-polymer fiber.
Thereby, it is possible to yield the optical device in which stray light can be avoided.
In the step d), light may be applied to the photo-curing resin mixed solution via a shrinkable mesh-like high-polymer member so as to form the fibers; and
then, the mesh-like high-polymer member may be caused to shrink so that the intervals of the fibers are shortened without disarrangement of the fibers, and, thus, the fibers are joined closely together.
Thereby, the fibers can be easily bundled without disarrangement of the fibers, automatically.
Further, the shrinkable mesh-like member may be enter a high-polymer gel state.
Thereby, no force is needed for changing the intervals of the fibers.
A method of manufacturing the above-mentioned image magnifying/reducing optical device, according to the present invention, comprises the steps of:
a) producing a plurality of thin plates each having a plurality of high-refractive-index regions; and
b) coupling the plurality of thin plates together.
The thin plates may be made of material which has a refractive index changed as a result of ultraviolet ray being applied thereto.
Thereby, it is easy to produce the pattern of the high-refractive-index regions by using a photo mask in application of ultraviolet ray. Accordingly, it is possible to yield the optical device according to the present invention by mass-production basis with low costs.
In each thin plate, the plurality of high-refractive-index regions may have a refractive index higher than that of a surrounding region, and have a two-dimensional pattern in which the plurality of high-refractive-index regions are apart from each other;
the plurality of thin plates are different in an area of each high-refractive-index region in many steps; and
in the step b), the plurality of thin plates are laminated together in the order of the area of high-refractive-index region, and in such a manner that the corresponding high-refractive-index regions are continuous through the plurality of thin plates.
Thereby, it is possible to produce the optical device according to the present invention by mass-production basis.
A method of manufacturing the above-mentioned image magnifying/reducing optical device, according to the present invention, comprises the steps of a) bundling a plurality of high-refractive-index fibers for the plurality of high-refractive-index regions, by using a mesh structure having variable intervals of elements thereof.
Thereby, it is possible to easily bundle the fibers with predetermined intervals.
A conic guiding member may be used for inserting each fiber of the plurality of high-refractive-index fibers into the mesh structure.
Thereby, it is not necessary to have a high positional accuracy in inserting the high-refractive-index fiber into the mesh structure.
The method may further comprise the step of coating adhesive on the fibers.
Thereby, the fibers can easily slide on each other, and, as a result, the bundling work can be performed easily. Also, fixing of the bundled fibers together can be easily performed.
At least a part of the fibers may be made of photo-curing resin.
Thereby, it is easy to produce the concave/convex end surface of the fiber according to the present invention.
A method of manufacturing the above-mentioned image magnifying/reducing optical device, according to the present invention, comprises the steps of:
a) bundling a plurality of high-refractive-index fibers for the plurality of high-refractive-index regions, so as to form a bundle of fibers; and
b) applying light into photo-curing resin mixed solution through the plurality of high-refractive-index fibers so as to form expanding tapered parts extending from one end of the bundle of fibers.
Thereby, the tapered parts can be produced easily and automatically.
The method may further comprise the steps of:
c) applying light into photo-curing resin mixed solution through the plurality of high-refractive-index fibers, after the step b), so as to form expanding tapered parts extending from the other end of the bundle of fibers.
Thereby, the tapered parts can be produced at both ends of the fibers easily and automatically. Accordingly, the above-mentioned shape of fiber according to the present invention in that the intermediate part is thinner than the end parts can be yielded.
The method may further comprise the steps of:
c) disposing a substrate having one of a convex shape and a concave shape for each fiber of the bundle of fibers; and
d) applying light toward the substrate in the photo-curing resin so as to form one of a concave shape and a convex shape on an end surface of each fiber of the bundle of fibers.
Thereby, the concave/convex end surface of the fiber can be easily and automatically produced.
The method may further comprise the steps of:
d) disposing a substrate having one of a convex shape and a concave shape for each fiber of the bundle of fibers; and
e) applying light toward the substrate in the photo-curing resin so as to form one of a concave shape and a convex shape on an end surface of each fiber of the bundle of fibers.
Thereby, the concave/convex end surface of the fiber can be easily and automatically produced.
The method may further comprise the steps of:
c) providing one of a light absorbing layer and metal film on a side surface of each high-polymer fiber.
The method may further comprise the steps of:
d) providing one of a light absorbing layer and metal film on a side surface of each high-polymer fiber.
Thereby, stray light between the fibers can be avoided.